1. Field of the Invention
The present invention relates to a door system for opening and closing a door, and more particularly a dual-purpose door system suitable for both an ordinary use and an emergency use.
2. Description of the Prior Art
A door system is of course normally provided upon a passenger vehicle such as, for example, a train, a bus, a plane and etc. the like. A known door system is designed for either of two purposes, that is, an ordinary use and an emergency use. There is also known a dual-purpose door system which is designed for both of these purposes.
A known door system for an emergency use which is provided upon a bus or a train car, where door systems for the two purposes are usually provided separately, is unsatisfactory in that it is necessarily equipped with auxiliary apparatus such as, for example, a stepladder for assuring the safe escape of the passengers from the deck floor onto the ground. Some train cars have installed with in the front wall thereof an emergency door which is adapted to pivot outwardly and downwardly, however, this type of door is restricted with respect to its installation location.
For an emergency escape, the dual-purpose door system is advantageous in that the passengers can use the same conveniently and safely in their accustomed manner and also in that it can be manufactured economically. Japanese Patent Application Pre-Examined Publication No. 61-110563 discloses such a dual-purpose door system. The disclosed system, however, has a drawback in that the effective dimension of the openable passage space of the system changes depending upon the operational mode. A door system widely openable in the ordinary mode renders the same narrowly openable in the emergency mode, or vice versa. The system has another drawback in that the size of the stepboard of the system restricts the dimension of the openable space of the system.